JPH0149897B2 - - Google Patents

Abstract

An electromagnetic inspecting apparatus for electromagnetically detecting a defect present in a magnetizable wire rope moving in its longitudinal direction is disclosed. The apparatus comprises a first magnetic pole disposed opposite to the elongate magnetic member, a second magnetic pole having a polarity different from that of the first magnetic pole and disposed opposite to the elongate magnetic member at a position spaced apart by a predetermined distance from the first magnetic pole in the longitudinal direction, a detecting core disposed opposite to the magnetizable wire rope at a position intermediate between the first and second magnetic poles, a detecting coil wound around the detecting core to make a differential response to flows of leakage flux appearing due to the presence of a defect in the magnetizable wire rope thereby generating an electrical output signal indicative of the result of its response, and a yoke magnetically coupling the first and second magnetic poles and the detecting core at the portions remote from the elongate magnetic member.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic flaw detection device for wire ropes, and relates to a device that can detect damaged parts with a simple configuration and high sensitivity.

[Conventional technology]

Generally, wire ropes used in cable cars and elevators tend to break or wear out locally during long-term use, and the remaining strength of the rope gradually decreases. As a general rule, ropes are inspected regularly and the rope is replaced based on its condition before an accident such as a rope breakage occurs. Ropes were previously inspected visually by maintenance engineers, but recently a method of inspecting for damage using magnetism has come into use. As an example, for example,
There are devices disclosed in Japanese Patent Publication No. 53-7290 and Japanese Patent Publication No. 43-9799.

[Problem to be solved by the invention]

However, since the above-mentioned prior art device directly detects leakage magnetic flux using a magnetic sensing element, a highly sensitive magnetic sensing element is required in order to detect weak leakage magnetic flux. The configuration becomes complicated due to the provision of multiple magnetic sensing elements,
Not only is it expensive, but also, on the other hand,
The device No. 7290 has poor operability, and the elevator uses multiple wire ropes, and the gap between adjacent wire ropes is about 5 to 6 mm, so this device was attached to the elevator wire rope. However, it is currently extremely difficult and almost impossible to run a wire rope or this device. In other words, the reality is that this device cannot be used for things like elevators, which have multiple wire ropes or are hung adjacent to each other.

Furthermore, when the device of Japanese Patent Publication No. 43-9799 is used for a wire rope with a twist pitch in which multiple strands are twisted together on the opposing surface, magnetic flux changes occur due to unevenness due to the twist pitch, and vibration noise and vibration are generated based on the unevenness caused by the twist pitch. However, there is a disadvantage that this oscillation noise cannot be distinguished from the output waveform due to the damaged part.

Therefore, the present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide a simple structure without being subject to any restrictions on usage conditions.
An object of the present invention is to provide a wire rope magnetic flaw detection device that can obtain stable measurement results.

[Means to solve the problem]

In order to achieve the above object, the features of the present invention are as follows:
A first magnetic pole and a second magnetic pole are arranged at a predetermined interval so that the magnetic pole faces face a wire rope running in the longitudinal direction, and the polarities of the respective magnetic pole faces are different from each other, The sides of the first magnetic pole and the second magnetic pole not facing the wire rope are connected by a yoke, and a detection core is connected to the central base of the yoke so as to face the wire rope, and the detection In a wire rope magnetic flaw detection device in which a detection coil is wound around an iron core, the first magnetic pole, the second magnetic pole, and the side of the detection iron opposite to the wire rope are each provided with the wire rope. a groove for accommodating the wire rope, and the depth of the groove is greater than or equal to a depth at which the wire rope does not protrude from the groove on a cross section perpendicular to the longitudinal direction of the wire rope; The distance between the magnetic pole and the second magnetic pole is an integral multiple of the twist pitch of the wire rope.

[Effect]

In the present invention, because of the above configuration, the magnetic flux conditions forming the part to be measured can always be the same regardless of the relative position due to the movement of the excitation body with respect to the wire rope, and it is possible to Since leakage magnetic flux from the damaged part can be captured regardless of the location of the damaged part, it is now possible to create a wire rope magnetic flaw detection system that is not limited by usage conditions and can obtain stable measurement results. can do.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

In this embodiment, in FIG. 1, 5 is a wire rope 2 whose one end is connected to the elevator car and the other end is connected to the counterweight 3 via the drive sheave 4A and the driven sheave 4B. This is a magnetic flaw detection device for an elevator wire rope that detects damage to a wire rope 2 that is installed facing the elevator and can be easily attached and detached.

As shown in FIGS. 2 and 3, this magnetic flaw detection device 5 has magnetic poles 6A and 6B disposed in the longitudinal direction of the wire rope 2, facing the wire rope 2, which is a long magnetic material. The two magnetic poles 6A and 6B are arranged in a positional relationship that is an integral multiple of the twist pitch SP of the wire rope 2, and the magnetic poles 6A and 6B are wound around the respective iron cores 7A and 7B so that the polarities of the magnetic poles are different from each other. An iron core 9 is provided, which has excitation coils 8A and 8B mounted thereon, and magnetically connected to the yoke 11 on the non-opposing sides of the wire rope 2 of the iron cores 7A and 7B, and a detection coil 10 is wound around the iron core 9. It has a fully equipped configuration. A recorder, display, alarm, or the like (not shown) is connected to the end of the detection coil 10. Further, the excitation coils 8A and 8B are both connected to a power source (not shown) via a switch.

Now, when the cross section is circular like the long magnetic wire rope 2, if the opposing surfaces of the wire rope 2 of the magnetic poles 6A, 6B and the iron core 9 are flat ends, the magnetic poles 6A and 6B and the iron core 9, respectively. The gap at both ends of the wire rope 2 in the direction perpendicular to the longitudinal direction is much larger than that at the center, increasing magnetic resistance and affecting the measurement results. Therefore, in practice, in order to guide the wire rope 2 so that the surfaces of the magnetic poles 6A and 6B and the iron core 9 facing the wire rope 2 correspond to the shape of the wire rope 2, in practice, U The U-shaped grooves 12A, 12B and 9A are formed, and the U-shaped grooves 12A, 12B and 9
A is formed in a groove with a depth greater than the depth at which the wire rope 2 does not protrude from the groove, and an insulating material 1 such as tetrafluoroethylene is provided as a sliding material on the inner surface of the groove.
3A, 13B and 13C are attached respectively.

The excitation coils 8A and 8B of the magnetic flaw detection device 5 configured in this way are excited, and for convenience of explanation, the excitation coils 8A and 8B have the surfaces of the magnetic poles 6A and 6B facing the wire rope 2, respectively. Excite the magnetic poles so that they become N and S poles, and move the wire rope 2 along the magnetic poles 6A and 6B and the iron core 9 in the longitudinal direction from the magnetic pole 6A to the magnetic pole 6B (in the direction of the arrow from left to right on the page). If you let
As shown in Fig. 4, magnetic pole 6B is formed by magnetic pole 6A, wire rope 2, magnetic pole 6B, and yoke 11 in the magnetic path.
A magnetic flux Φ ₀ flows from the magnetic pole 6A toward the magnetic pole 6A, and a magnetic flux ΦlN flows from the magnetic pole 6A toward the iron core 9 due to the magnetic pole 6A, wire rope 2, iron core 9, and yoke 11.
There is a magnetic flux Φls flowing from the magnetic pole 6B toward the yoke 11 due to the magnetic pole 6B, the yoke 11, the iron core 9, and the wire rope 2. The polarities of the magnetic flux ΦlN and the magnetic flux Φls are in opposite directions, and if there is no damaged part 2P in the wire rope 2, the magnetic flux ΦlN and the magnetic flux Φls cancel each other,
This is equivalent to the case where no magnetic flux exists in the iron core 9, and no induced voltage is generated in the detection coil 10. However, as shown in FIG. 4A, the damaged part 2P is
When facing A, at this time, the magnetic flux ΦlN in the iron core 9 decreases due to the leakage magnetic flux from the damaged part 2P, while the magnetic flux Φls in the iron core 9 is not affected by the leakage magnetic flux from the damaged part 2P, and the magnetic flux decreases. Since the magnetic flux is not reduced, a magnetic flux equal to the difference between the magnetic flux ΦlN and the magnetic flux Φls flows in the iron core 9, and the damaged part 2P
When the magnetic flux Φls and the magnetic flux ΦlN face the magnetic pole 6A, the above-mentioned change in the differential magnetic flux occurs, and the detection coil 10 generates an induced voltage corresponding to the difference between the magnetic flux Φls and the magnetic flux ΦlN due to this magnetic flux change. Then, the damaged part 2P moves toward the iron core 9, and a differential magnetic flux between the magnetic flux Φls and the magnetic flux ΦlN flows in the iron core 9 until the damaged part 2P faces the iron core 9 as shown in FIG. 4B. However, since there is no change in magnetic flux, no induced voltage is generated in the detection coil 10. Furthermore, when the wire rope 2 moves in the direction of the arrow and the damaged part 2P passes through the iron core 9 as shown in Fig. 4C from the position shown in Fig. 4B, the magnetic flux ΦlN in the iron core 9 Since it is no longer affected by the leakage magnetic flux from the damaged part 2P, the loss due to the leakage magnetic flux from the damaged part 2P disappears and the wire rope 2 returns to the state of the magnetic flux when it is intact, while the magnetic flux Φls in the iron core 9 is reduced to the damaged part 2P. As a result, a magnetic flux equal to the difference between the magnetic flux ΦlN and the magnetic flux Φls exists within the iron core 9, and moreover, the magnetic flux at the damaged part 2P
When the magnetic flux passes through the iron core 9, the difference magnetic flux changes as described above, and the detection coil 10 generates an induced voltage corresponding to the difference between the magnetic flux ΦlN and the magnetic flux Φls due to this magnetic flux change. Then, the damaged part 2P is the core 9
After passing through the magnetic pole 6B and passing through the magnetic pole 6B, a magnetic flux equal to the difference between the magnetic flux ΦlN and the magnetic flux Φls flows in the iron core 9, but the magnetic flux Since there is no change in
No induced voltage is generated in the detection coil 10. Moreover, when the damaged part 2P passes the magnetic pole 6B, the magnetic flux Φls in the iron core 9 is no longer affected by the leakage magnetic flux from the damaged part 2P, so there is no loss due to the leakage magnetic flux from the damaged part 2P, and the wire rope 2 returns to the magnetic flux state when it is intact, and the magnetic flux Φls in the iron core 9 changes, but since it becomes the same value as one magnetic flux ΦlN, the magnetic flux ΦlN and magnetic flux Φls of each other
As a result, no magnetic flux flows in the iron core 9, and therefore no induced voltage is generated in the detection coil 10.

In this way, each magnetic flux ΦlN due to magnetic flux change
The state of magnetic flux change in the iron core 9 based on the difference between the magnetic flux and the magnetic flux Φls is shown in FIG. A voltage corresponding to the voltage is induced, and the voltage waveform at this time is as shown in Figure 5B. First, at point a, where the magnetic flux change occurs, the magnetic flux change becomes negative, and the corresponding negative direction changes. A voltage is generated, and then at point b, the magnetic flux changes in the positive direction, and a corresponding positive voltage is generated, and the voltage value at this time is 2 times the rate of change at point a.
Since the voltage is twice as high as that at point a, the magnetic flux change at point c is in the negative direction and the rate of change is the same as at point a, and the induced voltage is the same as that at point a. The same voltage is obtained.

In this way, when the damaged part 2P exists within the measurement range, it is output as a significant impulse voltage, so the presence of the damaged part 2P can be easily discovered with a simple configuration.

Figure 6 shows a state in which a no-signal waveform a and a damaged part waveform b are recorded by a recorder.
This is the oscillation noise that appears in response to the twist pitch SP of the magnetic pole 6A, as mentioned above.
If the spacing between the magnetic poles 6B and 6B is set to an integer multiple of the twist pitch SP of the wire rope 2, a magnetic path with a constant period will be formed to the part to be measured in line with the twist pitch SP, so the vibration noise will be approximated by a sine wave. It has been experimentally confirmed that the damaged part waveform b and the no-signal waveform a, which is vibration noise, can be easily distinguished, and stable measurement results can be obtained.

On the other hand, it has been experimentally shown that the detected voltage of the damaged part waveform b becomes lower as the length l in the longitudinal direction of the wire rope 2 of the iron core 9 is larger than the diameter of the wire rope 2, and when it is made smaller, a detected voltage of an impulse waveform can be obtained. has been confirmed.

In addition, the length L in the longitudinal direction of the wire rope 2 of the iron cores 7A and 7B of each magnetic pole is given by d, which is the diameter of the wire rope 2 in order to uniformly magnetize the wire rope 2 and provide a magnetic flux of the required density. It has also been experimentally confirmed that the dimensions should satisfy the relational expression π/4·d ² <L ² . Furthermore, as described above, the depth H of the U-shaped grooves 12A, 12B, and 9A is set to be greater than or equal to the diameter of the wire rope 2, and a magnetic path is formed that surrounds the wire rope 2 in the part to be measured. Therefore, it is possible to detect damaged parts over the entire circumference of the wire rope 2, and the wire rope 2 to be measured during measurement can be
The magnetic flaw detection device 5 can be easily attached and detached, resulting in excellent operability. Further, as described above, insulating materials 13A, 13 are provided on the groove surfaces of the U-shaped grooves 12A, 12B, and 9A.
B and 13C are attached, so each core 7A,
Damage to each of the iron cores 7A, 7B, and 9 due to contact between the wire ropes 2 and 7B can be prevented, and the wire rope 2 can be moved smoothly.

FIG. 7 shows the magnetic flaw detection device 5 shown in FIGS. 2 and 3 housed in a frame 14 for easy handling, and is provided with a handle 15 so that it can be carried. Also, what is shown here is for three ropes 2A to 2C installed in parallel.
Each magnetic pole core and detection core each having three U-shaped grooves for independently storing the ropes 2A to 2C are located in the frame 14, and the three
Damage to the ropes 2A to 2C is detected simultaneously or separately. 17A,1
7B is the output terminal of the detection coil 10 (Fig. 2);
A recorder, display, alarm, etc. are connected to this terminal as necessary.

By the way, the above-mentioned embodiment can be used as long as the diameter of the rope to be measured is the same for each elevator, but if the diameter of the rope is different, a magnetic flaw detection device having a U-shaped groove matching the diameter of the rope may be prepared. I have to keep it.

Furthermore, even when measuring multiple ropes at the same time, magnetic flaw detection devices must be prepared for each different number of ropes.

In order to eliminate such inconveniences, the conditions of the measuring rope 2 (diameter,
Detection units 18 and 19 that match the number of ropes, rope spacing, etc.
is provided and is detachably attached to the common detection main body 20. Here, detection body 2
0 is equipped with approximately half the height of the magnetic pole cores 7A, 7B, excitation coils 8A, 8B, approximately half the height of the detection core 9, detection coil 10, and yoke 11 in FIG. On the other hand, the detection parts 18 and 19 are provided with the remaining half of each of the above-mentioned iron cores, and the arrangement thereof needs to be such that when the detection main body 20 and the detection part 18 or 19 are joined, the respective iron cores match each other.

In the above description, each core and yoke are separate bodies, but they may be formed into an integrated E-shaped core. In this case, the manufacturing process can be reduced and there are no joints, which reduces the magnetic resistance within the core. can. On the other hand, both magnetic poles 6A and 6B are composed of an iron core and an excitation coil, but it is also possible to replace these with permanent magnets.

Furthermore, although the above embodiments have been described for detecting damage to wire ropes, it is of course applicable to detecting damage to linear bodies, rod-shaped bodies, and plate-shaped bodies made of magnetic materials.

〔Effect of the invention〕

As explained above, according to the present invention, with a simple configuration, it is possible to always maintain the measurement point under the same conditions without being subject to restrictions on usage conditions, and safety during use is ensured. In addition, it is possible to realize a wire rope magnetic flaw detection device that can obtain stable measurement results.

[Brief explanation of drawings]

Fig. 1 is a schematic longitudinal sectional side view showing the applied state of the magnetic flaw detection device of the present invention, Fig. 2 is a partially cutaway side view showing the basic configuration of the magnetic flaw detection device of the present invention, and Fig. 3 is a line drawn from Fig. 2. 4 is a schematic diagram showing the damage detection state in the magnetic flaw detection device according to the present invention, FIG. 5 is a characteristic diagram showing the relationship between leakage magnetic flux and generated voltage according to FIG. 4, and FIG. Fig. 4 is a diagram of recorded waveforms detected, Fig. 7 is a perspective view showing the external appearance of the magnetic flaw detection device, and Figs. 8 and 9 are front views showing the attachment/detachment positions of the detection section and detection body of the magnetic flaw detection device, respectively. It is a diagram. 2...Wire rope, 6A, 6B...Magnetic pole, 9...
Iron core, 10...detection coil, 11...yoke.

Claims (1)

[Scope of Claims] 1. A first magnetic pole and a second magnetic pole are arranged so that their magnetic pole faces face a wire rope running in the longitudinal direction, and the polarities of the respective magnetic pole faces are different from each other. are arranged at a predetermined interval, the sides of the first magnetic pole and the second magnetic pole that are not opposite to the wire rope are connected by a yoke, and the yoke is located at the center base of the yoke so as to face the wire rope. In a wire rope magnetic flaw detection device in which iron cores are connected and a detection coil is wound around the detection core, the first magnetic pole, the second magnetic pole, and the detection core are opposed to the wire rope. each side has a groove for accommodating the wire rope;
The depth of this groove is greater than the depth at which the wire rope does not protrude from the groove on a cross section perpendicular to the longitudinal direction of the wire rope, and the depth of the groove is greater than the depth at which the wire rope does not protrude from the groove. 1. A magnetic flaw detection device for a wire rope, characterized in that magnetic poles are arranged such that the spacing between the magnetic poles is an integral multiple of the twist pitch of the wire rope. 2. The wire rope magnetic flaw detection device according to claim 1, wherein the groove is provided with a low-friction insulating material.